I asked about this code im throwing a cpl days ago in another thread but now i replaced the sensor and my gauge is still not working. Code is po118 for Engine coolant temp sensor circuit high voltage. Where should i start to looking for the source of the problem? Also i have done the gauge test and the gauge doesn't move and i ran my truck for a few minutes and no sign of it moving. With old sensor it would work for a minute (Sometimes) then slowly drop back down to "0" (120)
Thanks For The Help

 

Ok, two wires on the temp sensor. Tan/black is 5 volt signal to the sensor, verify you are indeed getting five volts there. (sensor unplugged.)

Return to PCM is Black/Light Blue. That should be LESS than five volts, cooler the engine, the lower the value should be. I would test that wire unplugged as well, and see if you are getting any voltage on it. (which you shouldn't when the sensor is unplugged...... If you are, need to trace it back, and find the short.

 

I tried checking the volts but i cant seem to figure out how this new volt meter works. If i plug the senor up backwards the tach on the gauge goes alll the way up and the motor stops idling high. IDK if this shows anything. Also, i looked at the wires and followed them back to underneath the battery i dont see anything wrong??? Everything looks normal no pinching or anything.

 

Key on, engine off, red probe goes into Tan/black wire, black probe just goes to ground somewhere. (should show five volts.)

Do the same with the other wire, and see what you get. (shouldn't see ANY voltage with sensor unplugged.)

 

I tested it earlier and i tested the battery first and it was 12.xx volts then i did the plug and it said 20 on the tan and 15 on the black?! doesnt make sense. Thats with the motor off. Then when i drove it a little it works when i shut the truck off and turn it back on. goes to about 200 then it slowly drops from there as if it is slowly dying..... Im stumped

 

Wonder where that's coming from...... it shouldn't do that...... you shouldn't be able to find 20 volts anywhere on your truck.......

 

Ill try again tomorrow but im stumped and this is causing my motor to idle high and im scared to drive it because i dont know how hot my motor is.

 

Got around the same readings as before?? maybe the tester is bad. Once again the temp gauge will work and go to temp then slowly decrease...

 

Did you put anything on the threads of the temp sensor? It's almost like it's losing its ground... but, that shouldn't matter, as it's a two wire sensor.......

Does the voltage supply, or signal voltage out of the sensor drop off as the engine warms? (Check supply side first.... if that goes down, well, yeah, you are going to get less out as well.)

 

I cant check it now to dark and raining but i did realize that when i was checking voltage it was dropping slowly by a steady .01 or so Also no i just threaded in the sensor no nothing......

(The ground wire is the black and blue i believe because when i follow it it goes all the way to a bolt on the driver side fender with a bunch of other wires....) maybe its just a diffrent wire that i just said and it was no helpful info that's why i separated it haha